A linear cutting charge is an explosive device for cutting a target object. A type of linear cutting charge is termed a linear shaped charge. Linear shaped charges are known from the prior art, for example from U.S. Pat. No. 4,693,181, and the product commercially known as “Blade” generic charge, demolition, linear, cutting/flexible, lightweight (CDLC/FL). In use, a linear shaped charge is applied to a target object for cutting. Upon detonation of an explosive element in the charge, a metal liner forms a metal slug which is projected as a cutting jet towards the target object. The cutting jet is linear, along a longitudinal axis of the charge, and therefore cuts the target object along a line defined by a configuration of the charge when applied to the target object. This may be a curved linear configuration. The shape and depth of the cut may be finely controlled, by selecting appropriate dimensions and explosive loadings in the charge. Accordingly, linear shaped charges have many and varied applications, both civil and military, where a clean and controlled cut is required. Given the high cutting power, linear shaped charges may be used to cut concrete or metallic structures, for example when breaching walls or demolishing building structures. The precision of the line and depth of the cut allows for delicate cutting operations, for example cutting of a bomb casing.
It is often desirable to use linear shaped charges underwater, for example to cut a structure underwater, for example a structural support or a hull of a boat. Presently, for operating a linear shaped charge underwater, a rigid vessel is used which encloses the linear shaped charge when applied to the target object, and reduces water penetration in, and the effect of underwater pressures on, the linear shaped charge. Such a method is awkward and problematic. The vessel is rigid, and therefore a target object may only be cut along a straight line or a line according with the shape of the vessel. Moreover, ends of the vessel, perpendicular the longitudinal axis of the linear shaped charge, enclose ends of the charge and therefore prevent cutting where the ends of the vessel contact the target object. Further, the vessel is ineffective at deeper common diving depths, for example at a depth of 15 meters from the surface, not least as it is bulky and awkward to manipulate, and the cutting charge has to expend energy cutting through a wall of the vessel between the charge and the target. Consequently, water penetration and pressure effects prevent satisfactory performance of the linear shaped charge.
It is an object of the present invention to overcome such disadvantages.